How To: Install On Sony’s Xperia Z3/Xperia Z3 Compact The Android Marshmallow Concept ROM

Last updated: July 1, 2020.

The Sony’s Xperia Z3/Xperia Z3 Compact

Sony has launched their Marshmallow Android Concept beta program.  Through this program, an accepted number of Xperia users are allowed to install the Marshmallow concept ROM on their devices and experience Android Marshmallow.  The devices used in this project were the Xperia Z3 and Z3 Compact.


The Android 6.0 Marshmallow Concept ROM’s are now available for users of the Xperia Z3 and Z3 compact who were not accepted into the initial program.  This FTF file can be installed using Sony Flashtool.  Follow along with our guide below to install Android 6.0 Marshmallow Concept ROM on a Xperia Z3 D6603 and Xperia Z3 Compact D5803.

Prepare your phone:

  1. This ROM should only be used with a Sony Xperia Z3 D6603 or Xperia Z3 Compact D5803. Make sure your phone is one of these by going to Settings> About Device and checking the model number.  Using this ROM with another device could brick the device.
  2. Charge phone so you have at least over 60 percent of the battery to ensure you don’t run out of power before flashing completes.
  3. Back up SMS messages, call logs and contacts. Back up important media content by copying them manually to a PC or laptop.
  4. Enable USB debugging by first going to Settings>About Device. In About Device, look for the build number.  Tap the build number 7 times to activate Developer Options.  Go back to Settings and then click Developer Options>Enable USB debugging.
  5. Install and set up Sony Flashtool on your device. After installing, open the Flashtool folder.  Open Flashtool> Drivers> Flashtool-drivers.exe.  Install the drivers: Flashtool, Fastboot, Xperia Z3/Z3 Compact
  6. Have an original data cable to connect your phone and a PC.


Note: The methods needed to flash custom recoveries, roms and to root your phone can result in bricking your device.  Rooting your device will also void the warranty and it will no longer be eligible for free device services from manufacturers or warranty providers.  Be responsible and keep these in mind before you decide to proceed on your own responsibility.  In case a mishap occurs, we or the device manufacturers should never be held responsible.


  •  Android 6.0 Marshmallow Concept ROM FTF file for your device
    1. For Xperia Z3 D6603: Download
    2. For Xperia Z3 Compact D5803: Download 


  1. Copy the files that you downloaded and paste them in Flashtool>Firmwares folder.
  2. Open Flashtool.exe
  3. Hit the small lightening button located on the top left corner of Flashtool. Select Flashmode.
  4. Select the FTF firmware file.
  5. On the right side, choose what you want wiped. We recommend wiping: Data, cache, apps log.
  6. Click OK and the firmware will begin preparing for flashing.
  7. When you get a prompt to attach your phone to your PC, do so by first turning it off then pressing the volume down key.
  8. Keeping the volume down key pressed, plug the data cable into your phone and the PC. You will need to keep the volume down key pressed until flashing ends.
  9. Flashtool will ask you for FSC script, click on Mo.
  10. When the phone is detected in Flashmode, flashing will start automatically.
  11. When you see Flashing ended or Finished flashing, you can let go of the volume down key.
  12. Disconnect your phone from the PC and reboot it.


Do you have Android 6.0 Marshmallow Concept ROM on your Xperia Z3 or Z3 Compact?

Share your experience in the comments box below.


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